1. Field of the Invention
The invention relates generally to systems and methods for performing spinal fixation. Specifically, the invention relates to drill guides, particularly those used for orthopedic procedures.
2. Description of the Related Art
Advancing age, as well as injury, can lead to degenerative changes in the bones, discs, joints, and ligaments of the spine, producing pain and instability. Under certain circumstances, alleviation of the problems can be provided by performing spinal fusion. Spinal fusion is a surgical technique in which two or more vertebrae of the spinal column are fused together to eliminate the motion between the fused vertebrae. Spinal fusion is used to treat conditions where the spine exhibits instability. Spine instability may result from causes such as fracture, scoliosis, and spondylolisthesis, where one or more vertebrae move in a forward direction relative to the other vertebrae. Spinal fusion with discectomy is also performed for herniations of the discs. This surgery involves removal of the affected disc and fusion of the adjacent vertebrae. Traditionally, bone grafts have been used to fuse the vertebrae, but various types of vertebral implants have also been used.
The use of bone fixation systems for treating bone conditions is well established. For example, a bone plate may be positioned over and surrounding the bone injury area and secured to the bone. The bone plate can be secured to the bone by bone screws or other similar fasteners inserted through holes in the bone plate and into the bone itself, sometimes positioned with a drill guide. The screws are tightened so that the bone plate holds the bone to be treated in place in order to insure proper healing. Early fixation devices tended to be applicable only to long-bone injuries, with only limited uses for lower lumbar spinal injuries and disorders. The use of plate/screw fixation systems later expanded, however, to include uses for spinal injuries, including fusion of vertebrae and fixation devices for treating cervical vertebrae injuries.